I use the following workflow.
add mp3 files to my folder on my mac machine update/change mp3 tags (mp3tag) import into rekordbox. analyse and add cue’s/loops convert/update collection to Engine Prime of the new/changed MP3 files with Denon Conversion Utillity (DECU) This app places the files and Engine Prime database on my portable HDD (USB3) This External HDD is the duplicated to my 2nd external HDD, this syncing I do with a app named Free File Sync. This app, like DECU, only copies the new/changed files, so no need to wait.
hope this helps